Batch mixer



FIG. 1 is a front left perspective view of a batch mixer showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a right end view thereof; and,

FIG. 4 is a rear right perspective view thereof.

The portions shown in broken lines form no part of the claimed design. 

CLAIM The ornamental design for a batch mixer, as shown and described. 